diff --git a/CHANGES.md b/CHANGES.md
index 3128315..d96bd12 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,6 +2,7 @@
 
 * Change abbreviate long titles under menu tab
 * Update Requests library 2.24.0 (2f70990) to 2.25.0 (03957eb)
+* Update urllib3 1.25.11 (00f1769) to 1.26.1 (7675532)
 
 
 ### 0.23.0 (2020-11-11 13:30:00 UTC)
diff --git a/lib/urllib3/_version.py b/lib/urllib3/_version.py
index 5a0ec53..cd4e7b0 100644
--- a/lib/urllib3/_version.py
+++ b/lib/urllib3/_version.py
@@ -1,2 +1,2 @@
 # This file is protected via CODEOWNERS
-__version__ = "1.25.11"
+__version__ = "1.26.1"
diff --git a/lib/urllib3/connection.py b/lib/urllib3/connection.py
index 5248741..2a5a3f8 100644
--- a/lib/urllib3/connection.py
+++ b/lib/urllib3/connection.py
@@ -228,7 +228,7 @@ class HTTPConnection(_HTTPConnection, object):
         else:
             # Avoid modifying the headers passed into .request()
             headers = headers.copy()
-        if "user-agent" not in (k.lower() for k in headers):
+        if "user-agent" not in (six.ensure_str(k.lower()) for k in headers):
             headers["User-Agent"] = _get_default_user_agent()
         super(HTTPConnection, self).request(method, url, body=body, headers=headers)